Detection of cavitation in hydraulic turbines
Detection of cavitation in hydraulic turbines
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DOI：
10.1016/j.ymssp.2004.08.006
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发表时间：
2006-05-01
影响因子：
8.4
通讯作者：
Coussirat, M
中科院分区：
文献类型：
--
作者：
Escaler, X;Egusquiza, E;Coussirat, M
为了评估实际水轮机中空化的检测，进行了实验研究。该方法基于对机器中测量的结构振动、声发射和流体动压的分析。所提出的技术已被检查在真实的原型遭受不同类型的空化。特别是，一台轴流转桨式水轮机、两台弗朗西斯水轮机和一台水泵水轮机已在现场进行了研究。此外，还对实验室中的一台弗朗西斯水轮机进行了试验研究。首先，简要介绍了水轮机空化现象的一般特征和发生空化的主要类型。本文的工作主要集中在最重要的几个方面，即由于其侵蚀力而引起的前缘空化、由于其影响机器性能而引起的气泡空化以及限制操作稳定性的尾水管旋流。气穴检测基于先前对气穴动力学及其在机器内的位置的理解。这些知识是从实验室设备（如高速空化风洞和缩小比例的涡轮机试验台）中的流动可视化和测量中获得的。主要技术是研究信号的高频频谱内容及其对给定频带的幅度解调。此外，在某些情况下也可以使用低频频谱内容。所选机器中发现的各种类型的气穴现象所获得的结果，并详细讨论的文件。对每种空化类型的最佳传感器、测量位置、信号处理和分析等方面进行了总结，以验证和改进检测技术。(c)2004爱思唯尔有限公司保留所有权利。
An experimental investigation has been carried out in order to evaluate the detection of cavitation in actual hydraulic turbines. The methodology is based on the analysis of structural vibrations, acoustic emissions and hydrodynamic pressures measured in the machine. The proposed techniques have been checked in real prototypes suffering from different types of cavitation. In particular, one Kaplan, two Francis and one Pump-Turbine have been investigated in the field. Additionally, one Francis located in a laboratory has also been tested.First, a brief description of the general features of cavitation phenomenon is given as well as of the main types of cavitation occurring in hydraulic turbines. The work presented here is focused on the most important ones which are the leading edge cavitation due to its erosive power, the bubble cavitation because it affects the machine performance and the draft tube swirl that limits the operation stability. Cavitation detection is based on the previous understanding of the cavity dynamics and its location inside the machine. This knowledge has been gained from flow visualisations and measurements in laboratory devices such as a high-speed cavitation tunnel and a reduced scale turbine test rig. The main techniques are the study of the high frequency spectral content of the signals and of their amplitude demodulation for a given frequency band. Moreover, low frequency spectral content can also be used in certain cases. The results obtained for the various types of cavitation found in the selected machines are presented and discussed in detail in the paper. Conclusions are drawn about the best sensor, measuring location, signal processing and analysis for each type of cavitation, which serve to validate and to improve the detection techniques. (c) 2004 Elsevier Ltd. All rights reserved.